High intensity printing lamp



March 26, 1968 w. N. SCHEPFE HIGH INTENSITY PRINTING LAMP 2 Sheets-Sheet 2 Filed Dec. 28, 1965 FIG. 4

' INVENTOR 0 WILLIAM N. SCHEPPE M, W,

ATTORNEYS United States Patent 3,375,366 Patented Mar. 26, 1968 hire ABSTRACT OF THE DISCLOSURE An improved cooling arrangement is provided for a high intensity lamp such as used for printing, photocopying and the like. The cooling arrangement includes means for directing cooling air against the high intensity light source and further directing the cooling air against the translucent cover of the lamp. Additionally the translucent cover includes spaced plates and cooling air is directed between the spaced plates.

The present invention relates to a high intensity printing lamp, and more particularly, to a high intensity printing lamp for photocomposing machines such as the step and machine.

Photographic materials such as photographic film are commonly used commercially in the photocomposing art. Such photographic film stretches with heat so that close register between the film and copy is lost as the film is heated. It is particularly important with the photocomposing of color work that there be close register between one color and another, since the separate colors are individually printed and will tend to separate if not closely aligned.

One method of preventing overheating of photographic material by a lamp is simply to move the lamp further away from the photographic material; but this is unsatisfactory as it increases the required exposure time. Another known method is to direct cooling air on the exposure surface to blow the heat away from the photographic material. This has also been found not to be effective and moreover such cooling air picks up room dust and deposits it on the working surfaces.

Accordingly it is an object of the present invention to provide a high intensity printing lamp which overcomes the aforementioned difllculty;

Another object of the present invention is to provide a new and improved high intensity lamp;

Yet another object of the present invention is the provision of a printing lamp which does not overheat the surfaces on which it is directed.

In accordance with these and other objects, there is provided anew and improved high intensity printing lamp for photocomposing and the like and including a generally diverging reflector positioned within an outer housing and employing a xenon lamp or mercury vapor lamp as the light source. In accordance with one aspect of the I present invention,-'a cover including spaced translucent plates close the reflector. The plates are provided with infrared reflecting surfaces to block the transmission of infrared rays while permitting useable light to pass therethrough. In accordance with another aspect of the present invention, air is directed against the xenon lamp and then strikes against the inner surface of the inner one of the translucent plates to provide for cooling the enclosed reflector area. In accordance with yet another aspect of the present invention, air is directed between the spaced translucent plates to provide cooling of the plates.

For a better understanding of the present invention, reference may be had to the accompanying drawings wherein:

FIG. 1 is a front view of the improved lamp with the translucent cover plates partially broken away;

FIG. 2 is a plan view of the high intensity lamp of FIG. 1, in broken away section;

FIG. 3 is a cross sectional side tensity lamp of FIG. 1; and

FIG. 4 is an electrical schematic of the control circuit for the lamp according to the present invention.

Referring now to the drawings, there is illustrated a high intensity lamp 10 according to the present invention. The lamp 10 includes an outer housing 11 of suitable material such as cold rolled sheet steel. In order to operatively position a suitable reflector 12, the housing 11 is open at its front, as indicated at 11a. The reflector 12 is of generally diverging shape, having its open end positioned adjacent the open front end 11a of the housing 11 and having an inner end supporting a suitable light source, here shown as a pulsed xenon lamp 14. The reflector 12 is of substantially square cross section with decreasing outward divergence from its inner end toward its open end. In the illustrated embodiment the reflector 12 is of crinkled aluminum to provide for some diffusion of light. The lamp 10 may be supported in any suitable manner as on a tripod or stand 15.

In order to block the transmission of infrared or heat rays from the xenon lamp 14 from striking against the illuminated surface, there is provided a cover means closing the open end of the reflector 12 and in the illustrated embodiment formed of a pair of spaced translucent plates 16 and 17. Each of the plates 16 and 17 is of the type which blocks the transmission of infrared rays while transmitting useable light. The plates may be treated by firing a suitable metallic oxide coating into the surface of Pyrex glass to provide the plates 16 and 17 with an infrared reflecting surface. The coated'surface of the plates 16 and 17 in the illustrated embodiment is faced toward thexenon lamp 14.

To provide for cooling the lamp 10, there is provided a pair of cooling fans 19 and 20 each driven by a suitable electric motor 21 and 22. The fans 19 and 20 in the respective top and bottom of the housing 11 are positioned to draw air through upper and lower air intakes 23 and 24 respectively and to force the air into an air duct or passageway 25. The air duct 25 is defined at its top and bottom by a port-ion of the upper and lower walls respectively of the housing 11, by the upper and lower surfaces of the reflector 12, and by partitions 26 and 27, FIG. 2, which divide the housing 11 to define the air duct 25. Moreover the remainder of the housing 11 defines suitable exhaust ducts 28 and 29 terminating in upper and lower air exhausts 30.

To provide for cooling the xenon lam-p 14 and the view of the high ininner area defined by the reflector 12 and the inner plate 17, therefis provided a pair of spaced air openings 32, FIG. 1, communicating with the air duct 25 and formed adjacent the inner end of the reflector 12 to direct air against the xenon lamp 14. Moreover the vertical sides I ofthe reflect-or 12 are provided with exhaust slots 33 to perm-it for the escape of air from the enclosed chamber. A baflle 34 spaced outwardly of each exhaust slot 33 is etfective to direct the .air toward the air exhausts 30 and to provide a reflective surface along the exhaust slots 33. It will be understood that air from the fans 19 and 20 which is forced into the air ducts 25 will in part be directed through the air openings 32 against the xenon lamp 14, and then will be directed forwardly to strike the inner surface of the plate 17 and exhaust through the vertical slots 33.

To provide for further cooling of the glass plates 16 and 17, the reflector .12 is provided with upper and lower air openings 36 communicating with the air duct 25 and directing air into the space between the spaced plates 16 and .17. The housing 11 is provided with opposed inwardly extending flanges 11b along its side walls to retain the glass, and upper and lower segments of inwardly extending flanges 11c position the glass while defining exhaust opening 37, FIG. 2, from the space between the plates 16 and 17. Consequently a portion of the air from the fans v19 and 20 forced .into the air duct will be directed through the air openings 36 between the plates 16 and 17 to exhaust through the openings 37 and provide for cooling of the plates 16 and .17. Moreover the side flanges 11d cover the edge of the glass plates 16 and 17 so as to shield the operators eyes.

It has been found that an 8000 Watt xenon lamp Without the heat blocking effect of the plates 16 and 17 will heat photographic material against which the light is directed to a temperature of around 200 E, which is not acceptable for commercial quality photocornposing; but by the use of the heat reflecting plates 16 and 17, the temperature of the photographic material can be held to below about 105 F. to provide an acceptable temperature for the photographic film.

The xenon lamp 14 in the illustrated embodiment is of the pulsed xenon type and may be controlled in any suitable manner. FIG. 4 schematically illustrates one suitable control for the xenon lamp 14. As therein illustrated the xenon lamp 14 is powered by a power transformer 40 which ma have a 650 volt secondary adapted to be connected to .a 220 volt primary. The primary is tapped at 41 to provide a 115 volt terminal for a starting circuit, while one end of the primary is connected to a suitable tap switch 42 to provide for correction in variations of line voltage. It will be understood that the light output of the xenon lamp varies approximately as the square of the applied voltage. A capacitor 43 is connected across the secondary of the power transformer 40. The xenon lamp 14 is also connected across the secondary of the power transformer 40 through a reactor winding 46 of a square Wave satura ble pulse reactor 47.

To provide positive starting of the xenon lamp 14, there is provided a starting circuit including a time delay relay 49 having a normally closed switch 50 effective to open approximately two seconds after initial connection to the power line. A starter transformer 52 is serially connected with the switch 50 across the 115 volt tap of the power transformer 40 and accordingly is provided with a 115 volt primary producing, in the illustrated embodiment, a 4000 volt secondary output. A capacitor 53 is connected across the secondary of the starter transformer 52. The secondary of the starter transformer 52 is serially connected with a spark gap 54 to a starting winding 55 in the pulse reactor 47. It will be understood that the starting pulse is fed through the starting Winding for approximately two seconds after switching on of the control circuit, thereafter the xenon lamp 14 is operated by the power transformer 40 limited by the impedance of the pulse reactor 47.

Although the present invention has been described by reference to only a single embodiment thereof, it will be apparent that numerous other modifications and embodiments may be devised by those skilled in the art and it is intended by the appended claims to cover all modifications and embodiments which will fall within the true spirit and scope-of the present invention.

4 What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A high intensity lamp for photocomposing and the like and comprising:

an outer housing open at the front;

a generally diverging reflector in said housing having an open end toward the front of said housing and an inner end;

a pulsed xenon lamp positioned within said reflector adjacent said inner end;

cover means closing said reflector and including spaced translucent plates, said reflector being provided with first air opening means adjacent said inner end and with second air opening means adjacent said cover means and being further provided with first air openings and second air openings both communicating with the space between said plates;

fan means; and

air duct means connecting said fan means with said first air opening means and with said first air open ings whereby a portion of the air from said fan means is directed against said xenon lamp and strikes against the inner one of said translucent plates and another portion of said air from said fan means is directed through said first openings into the space between said plates, said plates being provided with an infrared reflecting material on their surfaces.

2. A high intensity lamp for photocomposing and the like and comprising:

an outer housing open at the front having top and bottom air intakes;

a generally diverging reflector in said housing having an open end toward the front of said housing and an inner end;

a high intensity light source positioned within said reflector adjacent said inner end;

translucent cover means closing said reflector;

said reflector being provided with first air opening means adjacent said inner end and with said second air opening means adjacent said cover means;

fan means comprising a pair of fans one for each of said intakes;

air duct means connecting said fan means and said first air opening means whereby air from said flan means is directed against said light source and strikes against said cover means and is exhausted through said second air opening means; and

air exhaust means extending from said second opening means.

References Cited UNITED STATES PATENTS 1,008,661 11/1911 Meyer 240-47 X 1,909,947 5/1933 Greppin 240-47 X 2,295,863 9/ 1942 Paradi-s 240-47 2,798,943 7/1957 Prideaux 240-47 3,021,422 2/1962 Ogier et a1. 240-11.4 X

NORTON ANSHER, Primary Examiner.

D. L. J'ACOBSON, Assistant'Examiner, 

